In the game you have two distinct allegiances. When they refer to Human vs. Fallen, they are really refering to Kingdoms vs. Empires. So, you have 5 pre-generated Kingdom races and 5 pre-generated Empire races. These are
Kingdoms:
Altar
Tarth
Gilden
Amarian
Capitar
Empires:
Wraiths
Trogs
Umber
Kraxis
Quendar
Note 8 of these have pre-generated sovereigns for you to play.
Fallen also refer to the titans creation when they were running the world. Then the lands destruction and boom we are where the story takes place.
For more info-check out the Heirgamenon.